Class B end devices listen for downlink messages during ping slots. This allows applications to send messages to devices at predefined time slots, rather than waiting for a Class A uplink. When combined with multicast groups, this allows applications to send periodic downlinks to many devices at the same time.
Class C end devices continuously listen for downlink messages. This allows applications to send messages to devices at any time, instead of having to wait for a Class A uplink. When combined with multicast groups, this allows applications to send immediate downlinks to many devices at the same time.
This guide shows how to enable or disable Class C for an and device, and how to work with multicast groups.
It is also possible to create a Class B or Class C multicast group to send downlink messages to a group of end devices. A multicast group is a virtual ABP device, where multiple physical devices share the same DevAddr and session keys. It does not support uplink, confirmed downlink nor MAC commands.
LoRaWAN frames are encrypted on the application layer using the AppSKey. Once the end device is registered, you can choose to enforce or skip payload encryption. Skipping payload encryption will cause the Application Server to forward messages to integrations without any processing, for example it will neglect payload formatters. If you choose to skip payload encryption, integrations will be responsible for processing the message in order to understand it.